This proposal describes the Harvard Medical School (HMS) Vaccine Clinical Trials Unit (CTU), which is comprised of an administrative component at HMS, two Clinical Research Sites (CRSs) at Brigham and Women's Hospital (BWH) and Fenway Community Health Center (FCH), and is supported by a processing laboratory at Beth Israel Deaconess Medical Center (BIDMC). The CTU will be affiliated with the Vaccine Network and represents a continuation of the highly successful Harvard HVTU which has been the lead enrolling unit in the HIV Vaccine Trials Network (HVTN) for the past three years, which maintains consistently high scores in the Network Evaluation System, and whose members play important leadership roles in the HVTN. The CTU will be led by highly experienced clinical investigators in the field of HIV vaccines who have collaborated effectively for the past five years. Dr. Raphael Dolin will serve as Principal Investigator (PI) for the CTU, and Drs. Lindsey Baden and Kenneth Mayer will serve as CRS site-PIs for BWH and FCH respectively. Dr. Dolin will also oversee the supporting laboratory at BIDMC. The collaboration among the components of the proposed CTU takes advantage of the special strengths of each site and results in a synergy of activities toward the goals of the Vaccine Trials Network. The BWH CRS is a university-based site with strong ties to local college populations, medical center employees, and has broad-based research programs. FCH is a community-based health center with strong ties to gay, lesbian, bisexual, and transgender communities and with well developed relationships with communities of underrepresented minorities. The laboratory at BIDMC has well-established sample processing procedures and also has other highly developed HIV laboratory capabilities. The CTU and its component CRSs are fully established to carry out the broad spectrum of activities required by the Network. These activities are fully integrated under the guidance of the CTU, and include community outreach, recruitment, and education programs, a single community advisory board (CAB), a single common pharmacy, centralized sample processing, and coordinated quality management. Common standard operating procedures (SOPs) have been developed through the Harvard HVTU for both CRS sites. While this Unit has participated in a broad spectrum of HIV vaccine trials, the CTU has particular interest in studies of adenovirus vectors, novel adjuvants, and mucosal immunity. We project that the Harvard HVTU will follow 176 subjects in year 6 of the current award, and at least 146 subjects in year 1 of the proposed award. Thus, 80 to 100 subjects will be followed at each CRS annually. We also anticipate that we could expand to enroll 500 subjects for a Phase III trial when one is undertaken.